Determination Of Metal Elements In Food By Energy Dispersive X-Ray Fluorescence Spectrometry

Metal element in food and its content are closely related to many metabolic functions of human body. The major elements and trace elements in food are abundant in content and sustained vital movement.When your body exposed to too many major elements, it can create a toxic effect on the body health.At present, there are a lot of ways to detect metal elements in food, such as atomic absorption spectrometry, inductively coupled plasma atomic emission spectrometry, inductively coupled plasma mass spectrometry, high performance liquid chromatography, ion selective electrode method, stripping voltammetry, chemical luminescence method. Samples in these instrument methods are needed to be pretreated before detection.Pretreatment methods include dry ashing, wet digestion and microwave digestion. The traditional techniques are time-consuming, using corrosive reagent, labor intensity and polluting environment seriously. The quality of determined elements is a great loss in the process of pretreatment. So it is of great significance to inspect the content of metal elements in food fast and accurately.In this method, the sample powder was directly pressed into mould, calcium, potassium and iron in samples could be detected at the same time by energy dispersive X-ray fluorescence spectrometer.The best working conditions of energy dispersive X-ray fluorescence spectrometer had been optimized. The optimal pipe pressure was25kv and optimal current was300uA.When two aluminium filters, one molybdenum filter and one copper filter were used, lower background interference spectra could be got. Test time160s of each sample was determined.Using corn starch as substrate for pressing tablet in this study.2g sample powder were pressed in the mould with6Mpa pressure. The moisture content of the samples should be controlled below5%,and the sample surface should be kept smooth. In this case, the count value was higher. The method for determination of calcium, potassium and iron with energy dispersive X-ray fluorescence spectrometry was established. In this method,the detection limit of calcium was288.46mg/kg, the detection limit of potassium was370.37mg/kg,and the detection limit of iron was9.38mg/kg. The energy dispersive X-ray fluorescence spectrometry was taken methodological evaluation. Comparing values derected by energy dispersive X-ray fluorescence spectrometry with addition,they are not significantly different by statistics analysis(P>0.05), had a higher accuracy. The recovery rate of calcium was between98.42%and102.25%, the recovery rate of potassium was between98.58%and104.14%, the recovery rate of iron was between98.17%and104.24%. The relative standard deviation of calcium was between1.84%and3.42%, the relative standard deviation of potassium was between1.79%and4.05%, the relative standard deviation of iron was between1.95%and3.21%.Comparing values derected with flame atomic absorption method, values often kinds of commercial goods derected by energy dispersive X-ray fluorescence spectrometry were higher.Using these values dividing values derected by flame atomic absorption method by average recovery rate as the true values comparing values derected by this method with the true values, they were not significantly different(P>0.05).Energy dispersive X-ray fluorescence spectral analysis has the advantages of simple pretreatment, analysis quickly, saving time, multi-elements testing simultaneously and so on. Experiments shows energy dispersive X-ray fluorescence spectrometry can be used as rapid detection methods for metal elements in food.